Without one of these, certificates are not being checked.

The qe client calls one of the following in on_start handler,

domain.set_peer_authentication(SSLDomain.VERIFY_PEER, trustfile)
domain.set_peer_authentication(SSLDomain.VERIFY_PEER_NAME, trustfile)

Dispatch does something similar,

https://github.com/apache/qpid-dispatch/blob/b468642f3ad8fb451e9126f06e542d6e97f89237/python/qpid_dispatch_internal/tools/command.py#L170-L175

I did not find the need for this mentioned in the documentation.